The present invention relates to a disposal method of radioactive wastes containing sulfate group (SO.sub.4.sup.2-) and a device therefor, in particular, relates to a disposal method of radioactive wastes and a device therefor suitable for solidifying the radioactive wastes in a container by a solidifier such as cement.
In plants such as a nuclear power plant handling radioactive materials, radioactive wastes such as radioactive liquid waste and used-up ion-exchanger resin are produced. Conventionally, these radioactive wastes were, for example, after drying treatment, solidified in a container by a solidifier consisting of such as cement, asphalt, or plastics.
In these days, a disposal method was proposed in which such as liquid waste containing sodium sulfate among these radioactive wastes was subjected to heating and melting treatment by adding such as silicon dioxide in the presence of a reducer and solidified to solid glass wastes containing radioactive materials (JP-A-61-79200 (1986), for example). According to this disposal method, since sulfate group which is an active portion of the sodium sulfate is converted to a stable chemical state, the method has an advantage that a stable solidified body can be formed. In addition to the above patent publication, the disposal method of this kind is disclosed such as in JP-A-60-159699 (1985), JP-A-61-79199 (1986), JP-A-61-82199 (1986), JP-A-59-108995 (1984) and JP-A-63-171399 (1988).
In the above conventional art, sulfur oxides (SOx) are generated when the radioactive wastes are vitrified with the heating and melting treatment. The emission of SOx into an environment is not preferable from a viewpoint of such as acid rain. When SOx is collected for suppressing the emission to the environment, the collected SOx is finally converted into sulfate group, and which may necessitate to be treated again as radioactive wastes.